1. Field of the Invention
The present invention relates to an image processing apparatus and image processing method for generating image data for image recording using, as recording materials, a colored material and a high transmissivity material higher in transmittance than the colored material.
2. Description of the Related Art
An inkjet recording method is known as a typical example in a recording apparatus which records information such as a character or image on a sheet-like recording medium such as recording paper or film. Recently, various recording materials have been proposed in recording apparatuses employing the inkjet recording method. Typical examples are dye ink and pigment ink.
The color material of the dye ink exists as a very small molecule in a recording material. When the dye ink is used in the inkjet recording method, the color material penetrates into a recording medium and is fixed. When the second color material is applied a short time after the first color material is fixed in a recording medium, the second color material is fixed in the recording medium in a state in which it is mixed with the previously fixed first color material.
The color material of the pigment ink exists as a particle of about several ten nm in a recording material. The pigment ink whose color material exists as a particle is almost free from decomposition of the color material by light and dissolution into water. The pigment ink is superior to the dye ink in the weather resistance and water resistance of a character and image.
When the pigment ink is used in the inkjet recording method, the color material hardly penetrates into a recording medium and is fixed on the surface of the recording medium because the particle size of the color material is large. When the second color material is applied a short time after the first color material is fixed on the surface of a recording medium, the second color material is fixed on the previously fixed first color material. That is, for the pigment ink, color materials form recording layers in the recording order. Hence, there has been proposed a technique of obtaining the decorative effect of an image by controlling the recording order of pigment inks (Japanese Patent Laid-Open No. 2012-085123: to be referred to as “literature 1” hereinafter).
According to the technique in literature 1, a color material (colorless material) having a relatively high transmittance is fixed on an upper layer with respect to a color material (colored material) which is arranged on a relatively lower layer and has a relatively low transmittance. The colorless material fixed on the upper layer forms an optical thin film. By controlling the thickness of the colorless material, various colors (structural colors) by thin film interference are reproduced. The technique in literature 1 exploits the fact that the structural color is different from the color of a colored material on a lower layer. By controlling the thickness of a colorless material on an upper layer, a desired color image is formed to obtain the decorative/decorating effect.
The method in literature 1 utilizes thin film interference for the decorative/decorating effect of an image, but does not use it for improvement of the quality of an image.